Devices and Methods for Powering a Medical Device

ABSTRACT

Devices and methods for powering a medical device for sustained delivery of fluids or continuous monitoring of body analyte. The devices may comprise a pumping mechanism, a driving mechanism for activating the pumping mechanism to dispense fluid, and a power source coupled to the driving mechanism and having an energy storage cell for providing a pulsed power to the driving mechanism. The methods may be implemented by activating the driving mechanism using pulsed energy in the form of at least one pulse train pattern accumulated in and discharged from an energy storage component.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention claims priority to U.S. Provisional PatentApplication Nos. 61/008,693, entitled “System and Method for Powering anInfusion Pump,” filed on Dec. 21, 2007, and 61/065,142, entitled “Systemand Method for Powering an Infusion Pump,” filed on Feb. 8, 2008, thedisclosures of which are incorporated herein by reference in theirentireties.

FIELD

Devices and methods for sustained delivery of fluids and/or continuousmonitoring of body analyte are described herein. More particularly, aportable infusion, patch-like pump, adherable to the skin that can alsocontinuously monitor body analytes is described. Also provided herein isa fluid dispensing and/or body analyte monitoring device having a powersource and components for energy conservation.

BACKGROUND

Medical treatment of certain illnesses requires continuous drug infusioninto various body compartments, such as subcutaneous and intravenousinjections. Diabetes mellitus (DM) patients, for example, require theadministration of varying amounts of insulin throughout the day tocontrol their blood glucose levels. In recent years, ambulatory portableinsulin infusion pumps have emerged as a superior alternative tomultiple daily syringe injections of insulin for Type 1 (DiabetesMedicine 2006; 23(2):141-7) and Type 2 (Diabetes Metab 2007 Apr. 30,Diabetes Obes Metab 2007 Jun. 26) diabetes patients. These pumps, whichdeliver insulin at a continuous basal rate, as well as in bolus volumes,were developed to liberate patients from repeated self-administeredinjections and allow them to maintain a near-normal daily routine. Bothbasal and bolus volumes must be delivered in precise doses according toindividual prescription, since an overdose or underdose of insulin couldbe fatal.

The first generation of portable insulin pumps refers to a “pager-like”device with a reservoir contained within a housing. A long tube isprovided for delivering insulin from the pump attached to a patient'sbelt to a remote insertion site. The reservoir, delivery tube and thehypodermic cannula altogether constitute an “infusion set”. Therecommended time for replacing an infusion set is every 2-3 days toavoid local infection at the cannula insertion site. Most users,however, extend this period until the reservoir is empty, sometimes upto 7 days. Examples of such devices are disclosed in U.S. Pat. Nos.3,631,847, 3,771,694, 4,657,486, and 4,544,369. These devices representa significant improvement over multiple daily injections but suffer frommajor drawbacks, including large size, heavy weight and long tubing. Thesize and weight of these devices is primarily attributable to the sizeand number of batteries (i.e., AA or AAA-type) employed in the devicesfor supplying the required high energy demand of the motor, screen,alarms, and other components which consume energy.

These bulky devices with long tubes are uncomfortable and are rejectedby the majority of users because they interfere with daily activities,e.g., walking, running, and sports. To avoid the tubing limitations, asecond generation concept was proposed, directed to a remote controlledskin adherable device with a housing having a bottom surface adapted tobe in contact with the patient's skin, with a reservoir contained withinthe housing, and with an injection needle adapted for fluidcommunication with the reservoir. These skin adherable devices aredesigned for replacement every 2-3 days similarly to the currentlyavailable pump infusion sets. Most patients, however, prefer to extendthis period until the reservoir is empty. This concept is discussed inU.S. Pat. Nos. 4,498,843, 5,957,895, 6,589,229, 6,740,059, 6,723,072,and 6,485,461.

These second generation skin adherable devices still have at least twomajor drawbacks:

-   -   The entire device should be disposed every 3 days including all        expensive components (e.g., electronics, driving mechanism).    -   The device is still heavy and bulky, which is exceptionally        important drawback because the device should be directly        attached to the patient's skin and remain in place for at least        3 days. The main reason for the large size and heavy weight is        the size and number of batteries (e.g., AA, AAA or button-type)        that supply energy to the motor, alarms, and maintain a        communication link between the skin adherable device and the        remote control unit. For example, the voltage required by many        of the low voltage controllers and motors is 3 Volts, while the        output of the batteries is less than 1.6 Volts.

In U.S. Pat. No. 7,144,384 to Gorman et al., assigned to InsuletCorporation, a skin adherable device is disclosed. The patent discussesthat a large portion of the device is occupied by four silver-oxidebutton batteries positioned perpendicular to the longitudinal axis ofthe device, making the device thick (18 mm) and bulky. Moreover, due tohigh energy consumption, such batteries typically last only 3 days,forcing the user to dispose of the entire device every 3 days.

A third generation skin adherable device was devised to increase patientcustomization. An example of such a device is described in the co-owned,co-pending U.S. patent application Ser. No. 11/397,115 and InternationalPatent Application No. PCT/IL06/001276. This third generation devicecontains a remote control unit and a skin adherable patch unit (alsoreferred to as “dispensing patch unit”) that includes two parts:

-   -   Reusable part—containing the metering portion, electronics, and        other relatively expensive components.    -   Disposable part—containing the reservoir and in some        embodiments, batteries. A tube delivers the fluid from the        reservoir to an exit port that contains a connecting lumen.

This concept provides a cost-effective skin adherable device and allowsfor a diversity of features, including various reservoir sizes andvarious needle and cannula types.

In the co-owned, co-pending U.S. patent application Ser. No. 12/004,837and International Patent Application No. PCT/IL2007/001578, a fourthgeneration device is disclosed. This device is configured as a patchthat can be disconnected and reconnected to a skin adherable cradleunit. The patch can be remotely controlled or can be operated by buttonsthat are located on the patch as disclosed in the co-pending, co-ownedU.S. Provisional Patent Application No. 60/961,527. In thisconfiguration, the user can deliver a required bolus dose by repetitivebutton pressing according to a predetermined dose per button press(“Bolus buttons”).

The co-owned, co-pending U.S. patent application Ser. No. 11/706,606,the disclosure of which is incorporated herein by reference in itsentirety, discloses a device that contains a dispensing patch unit andan analyte sensing means (e.g., sensor). This dual function device hasthe same configuration that was outlined above and can also bedisconnected and reconnected at the patient's discretion.

Both third and fourth generation devices may use a single, small-sizedbattery. An example of such a battery is a zinc-air battery, asdisclosed in co-pending, co-owned U.S. Provisional Application No.60/961,484. These batteries have many advantages, including low weight,small size, low cost, long shelf lives, high specific energy and highstability. However, such batteries have a limited amount of storedenergy of about 0.3 W·h, while a single use zinc-carbon AA battery hasstored energy of about 1.2 W·h. AAA batteries, however, are more thanten times larger and heavier than zinc-air batteries. Therefore, inorder to enable employment of a small size power source, which haslimited stored energy, the energy consumption of the electricalcomponents of the dispensing patch should be reduced, especially theenergy consumption of the motor, which is the primary energy consumer.

The motor requires a substantial amount of energy for its operation: acurrent of about 500 mA and voltage of about 3 Volts, i.e., 1.5 Watts ofelectrical power. The power output of a zinc-air battery provides anelectrical current of 10 mA and voltage of about 1.2 Volts, i.e., 0.012Watts of electrical power. To provide the 3 Volts required by the motorand the CPU from a battery output of 1.2 Volts, a DC-DC step-upconverter is used. The current requirements are provided by a pulsedpower method, i.e., accumulating energy over a relatively long period oftime and releasing it very quickly, thereby increasing theinstantaneously supplied power. As such, the pulsed method is based ongenerating periodic pulses of high power.

It is, therefore, essential that the pulses' parameters (e.g., dutycycle, pulse duration, width and amplitude) comply with theelectromechanical properties of the motor (e.g., load, torque friction).This can be carried out, for example, by changing pulse durationaccording to the load on the motor, as discussed in U.S. Pat. No.5,774,426 to Mai Xuan Tu et al. The electrical load on the motor ismeasured to determined missed steps of the motor (i.e., momentaryfailure of the motor). The energy supply to the motor is increased upondetection of the missed steps. Unfortunately, this invention isapplicable only to a single phase step motor and it may require severaliterations (including additional missed steps of the motor and loss ofenergy) prior to actual supplying energy sufficient to rotate the motor.

Another method to control the motor electronically is based on changingthe duty cycle according to energy stored in an implanted infusiondevice power source, as discussed in U.S. Pat. No. 7,122,026 to Rogerset al. The duty cycle is increased to compensate for power sourcedepletion. Yet, some energy supply devices (e.g., zinc-air batteries)maintain nearly constant power supply even when depleted. Thus, applyingthis method would result in unnecessary energy consumption. This methodalso ignores other mechanical factors associated with the motor'soperation, such as inertia and load.

SUMMARY

A device for the delivery of fluid to a patient's body is provided. Thedevice may include a miniature and thin portable programmable fluiddispensing unit. The dispensing unit may be a small, low cost, portabledispensing patch unit which is adherable to the patient's body. Thedispensing unit may include two-parts: a disposable part and a reusablepart. A power source may be incorporated into the infusion device andmay include without limitation a single, small-sized, button battery.

In some embodiments, the dispensing unit includes a driving mechanismand pumping mechanism to dispense fluid from a reservoir to an outletport that can be connected to a cannula subcutaneously inserted in thepatient's body.

The device includes a motor (e.g., stepper motor or DC motor) requiringenergy for its operation. The amount of required energy may include acurrent of about 500 mA and voltage of about 3 Volts, i.e., 1.5 Watts ofelectrical power. A zinc-air battery provides a current of 10 mA and,voltage of about 1.2 Volts, i.e., 0.012 Watts of electrical power. Toprovide the 3 Volts required by the motor and CPU from a battery outputof 1.2 Volts, a DC-DC step-up converter is used. The currentrequirements are provided by a pulsed power method, i.e., accumulatingenergy over a relatively long period of time in a high capacitycapacitor and releasing it very quickly, thus, increasing theinstantaneous current and generating high power pulses for a shortperiod of time. The motor is provided with a sequence of customizedpulses, also referred to as a pulse train, each pulse beingcharacterized by its current, width, duty cycle and frequency. Eachpulse's width is adjusted to fulfill the power requirements of themotor, i.e., when changing the motor rotational velocity (e.g., duringacceleration or slow down), the pulses are wider than pulses associatedwith constant rotational velocity. It should be noted that although astepper motor rotates in a fixed angle with each pulse provided to it,the motor output (e.g., torque or steps per second) can be adjusted bycustomizing the pulses. For example, short duration pulses (e.g.,0.4-0.6 milliseconds) will result in higher rotational velocity comparedto long duration pulses (e.g., 0.9-1.2 milliseconds).

In some embodiments, the motor is provided with pulsed power that isadjustable according to its rotational velocity. In turn, when the motorvelocity changes, more power is provided to overcome the friction andinertia of the driving mechanism or pumping mechanism. On the otherhand, when the velocity remains constant, only minimal power is suppliedbecause only minor forces are exerted upon the driving mechanism orpumping mechanism. These forces may be utilized for stopping the pumpingmechanism, and thereby less power would be required to stop the motor.The motor rotational velocity can be measured by counting the motor'srevolutions per time unit as described in the co-owned, co-pendingInternational Patent Application No. PCT/IL2008/000642, filed May 11,2007, and entitled “Methods and Apparatus for Monitoring Rotation of anInfusion Pump Driving Mechanism,” the disclosure of which isincorporated herein by reference in its entirety. In some embodiments,the motor may utilize a step-up voltage converter and pulsed powermechanism.

In some embodiments, the device may include a miniature energy sourcewhich is a sufficient energy source by virtue of a dedicated energysaving method employed for controlling a motor driver. Such may considerthe driving mechanism's inertia and be implemented regardless of motortype, battery, pumping mechanism and other parameters andcharacteristics of the device.

In some embodiments, the device may employ an energy saving mode for theoperation of the dispensing unit.

In some embodiments, a power supply mode may exploit the rotationalinertia of the motor or pumping mechanism to save energy. In otherembodiments, the power supply mode may exploit friction forces appliedto the motor or pumping mechanism for saving energy.

In some embodiments, implementing the pulsed power method by using a lowpower source (e.g., zinc-air battery) and energy storage device (e.g.,capacitor), the motor cannot rotate for a long period of time without acontroller (e.g., CPU). This safety mechanism inherently restricts anuncontrolled motor rotation which may result in drug overdose, fatal tothe patient.

In some embodiments, the device includes a miniature dispensing unithaving a small and low power battery that is sufficient to supply energyfor the entire usage duration.

It is an object of some embodiments to provide accurate control of themotor's rotation while employing an energy saving mode.

It is an object of some of embodiments to provide a method to controlthe pulse parameters of the motor to save energy during the motoroperation.

The foregoing and other features, aspects, and advantages of the presentinvention will be more apparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 a-c show a single-part dispensing unit (FIG. 1 b), a two-partdispensing unit (FIG. 1 c) and a remote control unit.

FIGS. 2 a-b show a single-part dispensing unit (FIG. 2 a) and a two-partdispensing unit (FIG. 2 b) employing a peristaltic pumping mechanism.

FIGS. 3 a-b show a two-part dispensing unit employing a peristalticpumping mechanism.

FIGS. 4 a-b show a single-part dispensing unit (FIG. 4 b) and a two-partdispensing unit (FIG. 4 a) employing a syringe-piston pumping mechanism.

FIG. 5 shows a sensing and monitoring device for the control ofrotational movements of the driving mechanism and pumping mechanism.

FIG. 6 shows a block diagram of the dispensing unit including energysuppliers and consumers.

FIG. 7 shows a block diagram of an energy supply and motor control ofthe dispensing unit.

FIGS. 8 a-b show an energy storage device for providing pulsed power.

FIGS. 9 a-b show power versus time and current versus time plots of thepulsed power supplied by a capacitor.

FIGS. 10 a-b are plots illustrating rotational velocity and powerprofiles as a function of time as supplied to the motor.

FIGS. 11 a-b are plots illustrating alternative rotational velocity andpower profiles as a function of time.

FIG. 12 is a plot illustrating a pulse distribution required for a powerprofile as supplied to the motor.

FIG. 13 is a plot illustrating an energy distribution during a pulsetrain implementing the power profile shown in FIG. 10 b.

FIG. 14 is a plot illustrating an energy distribution during a pulsetrain implementing the power profile shown in FIG. 11 b.

FIG. 15 is a plot illustrating an example of a pulse train implementingthe rotational velocity shown in FIG. 10 a.

FIG. 16 is a plot illustrating an example of a pulse train implementingthe rotational velocity shown in FIG. 10 a.

FIG. 17 is a plot illustrating an example of a pulse train implementingthe rotational velocity shown in FIG. 11 a.

DETAILED DESCRIPTION

A dispensing unit (10) and a remote control unit (40) are describedherein. In some embodiments, the dispensing unit (10) may include asingle part (as shown in FIG. 1 b) or two parts (as shown in FIG. 1 c).The two-part dispensing unit includes a reusable part (100) and adisposable part (200). The dispensing unit (10) may employ differentdispensing mechanisms, including without limitation a syringe-typereservoir with a propelling plunger, peristaltic positive displacementpump In some embodiments, the dispensing unit (10) can be adhered to thepatient's body by a skin adherable cradle unit. An example of such acradle unit is disclosed in the co-owned, co-pending U.S. patentapplication Ser. No. 12/004,837 and International Patent Application No.PCT/IL2007/001578, the disclosures of which are incorporated herein byreference in their entireties. The term “dispensing unit” is not limitedto fluid delivery. In some embodiments, the dispensing unit (10) may becapable of dispensing fluid (e.g., insulin) to a patient's body orsensing analyte (e.g., glucose) in the body.

Infusion programming, data transferring and control of the dispensingunit (10) can be carried out by a remote control unit (40), which may beconfigured as a personal digital assistant (“PDA”), a hand watch, acellular phone, or any other means. The remote control unit (40) iscapable of establishing a unidirectional communication with thedispensing unit (10), i.e., the remote control unit (40) only transmitsdata to the dispensing unit (10) or only receives data from thedispensing unit (10). The communication link between remote control unit(40) and dispensing unit (10) can be also bidirectional, i.e., theremote control unit (40) is capable of transmitting and receiving datato and from the dispensing unit (10).

FIGS. 2 a-b show exemplary embodiments of the dispensing unit (10)employing a peristaltic pumping mechanism for dispensing fluid to auser's body. FIG. 2 a shows a single-part dispensing unit (10). Thefluid is delivered from a reservoir (220) provided in the dispensingunit (10) through a delivery tube (230) to an exit port (213). Theperistaltic pump includes a rotary wheel (110) provided with rollers(not shown) and a stator (190). Rotation of the rotary wheel (110) andperiodic squeezing of the delivery tube (230) against the stator (190)positively displaces fluid from the reservoir (220) to the exit port(213). An example of such a positive displacement pump is disclosed inthe co-owned, co-pending U.S. patent application Ser. No. 11/397,115,filed on Apr. 3, 2006, the disclosure of which is incorporated herein byreference in its entirety. A driving mechanism (120) for rotating therotary wheel (110) can be provided. The driving mechanism (120) includesa gear and a motor. The motor can be a Stepper motor, a DC motor, SMAactuator or any other motor. The driving mechanism (120) is controlledby electronic components (130) residing in the dispensing unit (10). Theelectronic components (130) may include a controller (not shown), aprocessor (132), a transceiver (131) and/or a transmitter (133). Anappropriate power source (240) and an energy storage device (252) (e.g.,a capacitor) are also provided. The power source (240) may includewithout limitation one or more batteries, such as a button-sizedzinc-air battery.

In some embodiments, the power source (240) may be a button battery andthe energy storage device (252) may be a high capacity (e.g., about 0.2F) capacitor. Using a button battery usually requires the supply ofpulsed power in order to increase the current output by the battery. Thepulsed power mode is established by periodically charging anddischarging the high capacity capacitor. Infusion programming of thedispensing unit (10) can be carried out either by remote control unit(40) and/or by manual buttons (15) provided on the dispensing unit (10).

FIG. 2 b shows a two-part dispensing unit (10) that includes a reusablepart (100) and a disposable part (200). The reusable part (100) includesa positive displacement pump provided with rotary wheel (110), drivingmechanism (120), and electronic components (130). The disposable part(200) includes reservoir (220), delivery tube (230), power source (e.g.,button battery) (240), energy storage device (252), exit port (213), andstator (190). Pumping is enabled upon attachment of the two parts toeach other. This arrangement is discussed in the co-owned, co-pendingU.S. patent application Ser. No. 11/397,115, filed on Apr. 3, 2006, thedisclosure of which is incorporated herein by reference in its entirety.The power source (240) may also be located in the reusable part (100)and can be rechargeable.

FIGS. 3 a and 3 b show respectively an embodiment of the two-partdispensing unit (10) prior to (as shown in FIG. 3 a) and subsequent to(as shown in FIG. 3 b) connection of the two parts. The reusable part(100) contains a peristaltic pumping mechanism provided with rotarywheel (110) and a driving mechanism (120) having a motor (121), a worm(126), a shaft (128) and gears (124). The reusable part (100) alsocontains electronic components (130). The disposable part (200) includesreservoir (220), delivery tube (230), power source (240), exit port(213), and stator (190). The power source (240) may be a zinc-airbattery or button battery.

FIGS. 4 a-b show embodiments of the dispensing unit (10) employing apiston-plunger pumping mechanism for dispensing fluid to a user's body.FIG. 4 a shows a two-part dispensing unit (10) having a reusable part(100) and a disposable part (200). The disposable part (200) includesreservoir (220) provided with plunger assembly (110), power source(e.g., battery) (240), energy storage device (252), and exit port (213).In alternative embodiments, the plunger assembly (110) may be located inthe reusable part (100) or be shared by both parts. The reusable part(100) includes a driving mechanism (120), which has a motor (121) (e.g.,Stepper motor, DC motor, or SMA actuator) and a driving gear (not shown)for displacing the plunger assembly (110). The driving mechanism (120)is controlled by electronic components (130), which has a controller(not shown), a processor (132), a transceiver (131), and/or atransmitter (133). Infusion programming can be carried out by a remotecontrol unit (not shown) and/or by one or more buttons (15) provided onthe dispensing unit (10). The power source (240) may be located in thereusable part (100) and may be rechargeable. An example of such adispensing unit is disclosed in the co-owned, co-pending U.S.Provisional Patent Application No. 61/123,509, filed on Apr. 9, 2008,the disclosure of which is incorporated herein by reference in itsentirety.

FIG. 4 b shows a single-part dispensing unit (10), which includessubstantially similar components as the two-part dispensing unit (10).The components of the single-part dispensing unit (10) are deployedwithin a common housing (11). The embodiments shown in FIGS. 4 a-b aredisclosed in the co-owned, co-pending International Patent ApplicationNo. PCT/IL2008/000641, the disclosure of which is incorporated herein byreference in its entirety.

Any of the above-mentioned embodiments may be provided with a sensingand monitoring device for controlling operation of the driving mechanism(120). FIG. 5 shows this device employing a photo interrupter (113) asdisclosed in the co-owned, co-pending International Patent ApplicationNo. PCT/IL2008/000642, the disclosure of which is incorporated herein byreference in its entirety. The sensing and monitoring device is providedwith an encoder vane (116) configured as a 180 degree sector, which isaffixed to a shaft (128) such that the encoder vane (116) rotates withthe shaft (128) at the same rotational velocity. Photo-interrupter (113)is positioned such that as encoder vane (116) rotates it passes throughspace (S) between LED (112) and light detector (114). The motor's (121)rotational velocity can be derived from the shaft's (128) rotationalvelocity by taking into consideration the gear (124) reduction ratio.For example, when the shaft (128) rotates at 1 rotation per minute (RPM)and the gear (124) ratio is 3:1; the motor's (121) speed is 3 RPM. Othersensing and monitoring devices may also be employed to measure themotor's (121) rotational velocity.

FIG. 6 shows schematically the power source (240) and energy consumingcomponents of the dispensing unit (10) controlled by controller (132).The energy consuming components include:

-   -   a communication device (134), which may include without        limitation RF, IR and other communication types (e.g., magnetic        relay, manual buttons, audible commands).    -   a pumping mechanism (136) actuated by a driving mechanism having        a motor and motor driver.    -   a sensing and monitoring device (138), which may include without        limitation an occlusion sensor or motion sensor.    -   an indication device (140), (also referred to as “notification        device”), which may include without limitation a buzzer or        vibration alarm.

FIG. 7 shows a flow chart depicting an energy supply and control of themotor (121). In practice, a low price, small-sized power source (240)(e.g., button battery) may be used, particularly a small quantitythereof, to provide a dispensing unit (10) that is of miniature size andlightweight. Due to the small size of a button battery, the electricalpower output produced thereby, i.e., current (“i”) and voltage (“v”), issubstantially lower than the electrical power required for motoroperation, i.e., a condition is satisfied whereby

i _(battery) ·v _(battery) <<i _(motor) ·v _(motor) or W _(battery) <<W_(motor)

For example, a zinc-air battery has a maximum power output of about 0.03Watts (e.g., current of about 25 mA and voltage of about 1.2 Volts),while the motor (121) requires electrical power of 1.5 Watts (e.g.,current of about 500 mA and voltage of about 3 Volts). It can be seen inthis example that the electrical power (W_(motor)) required by the motoris 50 times larger than what the battery (W_(battery)) is able tosupply. The electric power required by the motor is not limited to theparticular electrical power indicated above.

Thus, in order to enable operation of the motor (121), the voltage andcurrent supplied thereto are increased. Voltage increase can be carriedout by virtue of a DC-DC converter (254) which can for example convertthe 1.2 Volts supplied by the battery, i.e., power source (240), to thevoltage required by the motor (121), i.e., 3 Volts. Increasing thecurrent can be carried out by a pulsed power method, i.e., by chargingthe energy storage device (252) (e.g., a 0.2 F capacitor) forapproximately 1 second and then discharging it for about 20milliseconds. This enables multiplication of the current by 50 times.

The 3V voltage is also supplied to the controller (132) and to thesensing and monitoring device (138) (e.g., revolution counters). Such asensing and monitoring device (138) is disclosed in the co-owned,co-pending International Patent Application No. PCT/IL2008/000642, asnoted above. The motor driver (255), which is controlled by thecontroller (132), operates the motor (121) by providing it with a pulsedpower, as shown by line (109). The pulsed power is supplied by theenergy storage device (252).

In some embodiments, the motor's (121) operation is controlled by theprinciple of a closed-loop feedback, according to which the amount ofpower supplied to the motor (121) is adjusted based on the motor's (121)rotational velocity (38). Sensing and monitoring device (138) (e.g.,revolution counter or rotation sensor) measures the motor's (121) outputas shown by dashed line (22) and provides the controller (132) with therequired data, including without limitation, the motor's (121) instantrotational velocity, as shown by dashed line (38). In some embodiments,the sensing and monitoring device (138) merely provides a number ofrevolutions of the motor (121), while the velocity is calculated by thecontroller (132). In some embodiments, the motor's (121) mechanicalenergy may be converted into electrical energy, as shown by line (108).This energy can be stored in the energy storage device (252) for lateruse.

FIGS. 8 a-b show the main components depicted in FIG. 7: the motor(121), the energy storage device (252), and the power source (240)connected by flat strip connectors (241) to other electrical components(130). The energy storage device (252) can be a high capacity capacitorhaving a capacity of 180 mF to 200 mF. It is advantageous if thecapacitor has a flat configuration and reduced dimensions (e.g., 29mm×17 mm×0.9 mm). Consequently, the capacitor may be placed parallel tothe electronic components (130) (e.g., a printed circuit board), whichallows the dispensing unit (10) to be kept as small and thin aspossible. In practice, the capacitor having the above-mentionedconfiguration and dimensions provides a dispensing unit having thicknessless than 15 mm.

FIGS. 9 a-b are power-time plots illustrating a pulsed power produced bya capacitor and supplied to the motor. In some embodiments, the supplyof pulsed power includes two modes: accumulation mode (400) and releasemode (500). During the accumulation mode (400), a battery charges thecapacitor. During the release mode (500), the capacitor is beingdischarged and supplies current to power consuming components of thedispensing unit, including without limitation, the motor and electronicelements.

The ratio between the accumulation time (“t_(accumulation)”) and releasetime (“t_(release)”) is proportional to the ratio between the powerrequired for operation of power consuming components, such as a motor(“W_(motor)”) and the electrical power outputted by a battery(“W_(battery)”), i.e.,

$\frac{t_{accumulation}}{t_{release}} \propto \frac{W_{motor}}{W_{battery}}$

FIG. 9 a shows a graph of a typical charging/discharging cycle of thecapacitor having the two modes. It is clear that the duration of theaccumulation mode (400) is substantially longer than the release mode(500). In practice, this duration may be 50 times longer. Therefore, themaximal pulse train duration applied for activating the motor is lessthan the release mode (500) duration. In alternative embodiments, thecharge stored in the capacitor may be monitored (e.g., by an A/Dconverter), thereby allowing a dynamic control over the discharging andrecharging of the capacitor to be achieved.

FIG. 9 b shows schematic graphs of the power (“Power”) and current (“i”)of a charging/discharging cycle of the capacitor. During accumulationmode (400), the energy that is supplied by the battery is accumulatedand stored in the capacitor. In practice, when applying a 0.2 Fcapacitor and a zinc-air battery, it may take 980 milliseconds. Theenergy (p₁) that is stored in the capacitor gradually increases whilethe supplied current (i₁) remains constant. During the release mode(500), the capacitor discharges and, supplies the required amount ofpower to the power consuming components. When the capacitor has 0.1 Fcapacity and the battery is a silver-oxide button-sized battery with0.186 Watt output, the release mode can take 10 milliseconds, while theaccumulation time is about 8 times higher. Discharged power and currentare designated as p₂ and i₂, respectively. In some embodiments, theremay be continued charging of the capacitor, even during the dischargephase, which shortens the time interval between two consecutive pulses.If the capacitor is fully loaded, the charging process may not continue.

FIG. 10 a shows the angular velocity (ω_(m)) of the motor versus time(t) and FIG. 10 b shows the corresponding power (P) discharged from thecapacitor and supplied to the motor. During this period, the motoroperates the pump to deliver fluid (e.g., insulin) via the dispensingunit. When the motor is rotated based on energy from the capacitor onlya limited amount of fluid can be delivered during a singlecharging/discharging cycle and, therefore, more than one cycle may berequired to deliver the appropriate amount of fluid required fortherapeutic treatment.

In some embodiments, a variant pulse train can be supplied to the motoreach time the capacitor is being discharged. The amount of powersupplied during the discharge of the capacitor depends upon whether themotor rotates with constant or variable rotational velocity.

At t=t₀, the motor begins to rotate and its rotational velocity shouldbe gradually increased up to a certain velocity. The increasing velocityis designated as a₁. The velocity increases due to supplying a certainamount of electrical power delivered by the capacitor to the motor(P>0). This power is designated as b₁. At t=t₁, the motor's angularvelocity is constant, as represented on the graph in FIG. 10 a as aplateau. The achieved velocity is designated as a₂. The amount of powerrequired to keep the motor rotating at constant velocity a₂, can be b₂,which is less than b₁ since constant angular velocity (ω_(m)) ismaintained due to inertia. Thus, the required power (b₂) is less thanb₁. During the time interval from t=t₂ to t=t₃, the velocity of themotor is decreased until full stop (the decreasing velocity isdesignated as a₃). The velocity can be reduced by supplying power b₃, asmay be required to overcome inertia until stopping the motor. In someembodiments, the time interval from t=t₁ to t=t₃ is about 20milliseconds.

The pattern of the pulses is typically predetermined when the pulsetrains are tailored. That is, the dispensing pump is initiallyconfigured with at least one pulse train. In some embodiments, thedispensing pump controller can adjust and combine various pulses andpulse trains as needed. In other embodiments, the controller can adjustand schedule the pulse train (e.g., energy, number of pulses, width ofpulses, or frequency) based on the energy stored in the energy storagedevice or power source.

FIGS. 11 a-b refer to another embodiment and show graphs of the angularvelocity (ω_(m)) of the motor versus time (t) and the correspondingpower (P) required by the motor versus time (t). The graphs depictvariations in velocity and power during drug delivery, while analternative operational mode of the motor is employed for saving energy.The two first phases designated by a₁, a₂ and b₁, b₂ are identical tothose referred to in FIGS. 10 a-b. During the time interval starting att=t₂ and ending at t=t₃, the velocity of the motor is decreased merelydue to friction forces until a full stop (the reducing velocity isdesignated in FIG. 11 a as a₄). FIG. 11 b shows that in this timeinterval (t=t₂ to t=t₃), the motor continues to rotate and no energy isrequired. Therefore, energy associated with the rotation of the motor isavailable for use by the energy consuming components while the motoritself does not require supply of energy, i.e., during this phase themotor may operate like a dynamo.

FIG. 12 shows current (i) supplied to the motor versus time (t), duringa pulse train employing the operation mode described in FIGS. 10 a-b.The current (i) is supplied by pulses while each pulse is characterizedby a time interval (“t”) (i.e., a period). The initial pulse (e.g.,between t₁ and t₂) has long period t₁, typically lasting for 1 to 1.5millisecond, for setting the driving mechanism into motion and foraccelerating the motor. The duration of each consecutive pulse is eitherequal or shorter than the former. In some embodiments, the second phasehas a minimal pulse period t₂ of about 0.5 milliseconds. This trend isturned over when the motor speed is decreased, i.e., in this phase themotor is decelerating and each period t₃ of each pulse is either equalor longer than the former.

For example, the duration of the n pulses of an exemplary pulse traincan be written as shown in the following equation:

t₁≧t₂≧t₃≧ . . . ≦t_(n-1)≦t_(n)

Since a pulse duration (t) is inversely proportional to the angularvelocity of the motor (ω), (t∝1/ω), the above equation can beaccordingly rewritten as follows:

ω₁≦ω₂≦ω₃≦ . . . ≧ω_(n-1)≧ω_(n)

According to some embodiments, every pulse is tailored to rotate themotor's axis through an identical angle (known as a ‘step’). Enabling aconstant angular rotation resulting from each discrete pulse andproviding the same amount of fluid is highly advantageous in that itsimplifies the dispensing pump control and calibration, for example,when calculating the number of pulses needed to deliver a requiredamount of therapeutic fluid. This is achieved by maintaining constantthe multiple of pulse duration by the rotational velocity it causes:

t ₁·ω₁ =t ₂·ω₂ =t ₃·ω₃ = . . . =t _(n-1)·ω_(n-1) =t _(n)·ω_(n)=18⁰

FIGS. 13-14 shows current (i) supplied to the motor versus time (t),according to some embodiments. Conventional methods for supplying energyto motors of infusion devices employ pulses in which a constant level ofpower is provided to the motor during each pulse period (i.e., a 100%duty cycle). This method can be employed to the device disclosed hereinas well, i.e., power pulse trains may be supplied to the motor whileeach pulse train includes pulses of power during which power would besupplied non-invariantly at three various levels b₁, b₂ and b₃ lastingduring respective periods t₁, t₂ and t₃ following without interruption.

In some embodiments, supply of power may be organized during each pulsewith interruptions. As shown schematically in FIG. 13 there could beprovided three different operational phases and each pulse of the pulsetrain includes:

-   -   A discharge phase (510)—pulsed power is provided to the motor by        discharging a capacitor.    -   A null phase (520)—power supply is interrupted and power is not        supplied to and neither generated by the motor.    -   A charge phase (530)—energy is generated by the motor and this        energy can be supplied to power consuming components.

The pulses typically include discharge (510) and null (520) phases ornull (520) and charge (530) phases but may include only discharge (510)or charge (530) phases.

FIG. 13 shows a graph of the current (i) supplied to the motor versustime (t), for generating the angular velocity according to principlesdescribed in connection with FIGS. 10 a-b. The graph shows a singlepulse train, which includes three initial pulses. Each one of initialpulses (e.g., the pulses designated as p₁, p₂ and p₃) have two phases: adischarge phase (510) (designated as w₁, w₂ and w₃), followed by a nullphase (520).

In some embodiments, the null phase (520) is 10% to 30% of the pulseperiod, i.e., the width of these pulses is of 70% to 90%. In someembodiments, the dispensing pump controller applies pulse widthmodulation (PWM) for changing the width of the pulses to generate thedetermined pulse train. It should be appreciated that other methods forexploiting the motor's inertia for reducing the energy supply may beimplemented, such as by changing the pulse period, amplitude, or shape(e.g., triangle, square, sine wave).

Halting motor operation is carried out by the last pulses of the pulsetrain (e.g., p_(n-1) and p_(n)). The discharge phase (510) of thesepulses equals the duty cycle; p_(n-1)=ω_(n-1) and p_(n)=ω_(n). Thiscauses the motor to stop almost immediately, so that no excess fluid isdelivered by the dispensing unit.

FIG. 14 shows a graph of current (i) supplied to the motor versus time(t), for implementing the principle described above in connection withFIGS. 10 a-b. The graph shows a pulse train. The last pulses of thepulse train (e.g., p_(n-1) and p_(n)) include a single phase, i.e., thecharge phase (530). This mode of operation enables the motor to generateenergy due to its rotation and to transfer it to an energy storagedevice.

The halting method is shown in FIGS. 11 a-b and may require the use of asensing and monitoring device (e.g., a sensor) to detect the relativeposition (i.e., angle) of the rotary wheel. The sensing and monitoringdevice may be required to achieve an accurate fluid delivery employing aflow correction mechanism.

Although particular embodiments have been disclosed herein in detail,this has been done by way of example for purposes of illustration only,and is not intended to be limiting with respect to the scope of theclaims. In particular, it is contemplated by the inventors that varioussubstitutions, alterations, and modifications may be made withoutdeparting from the spirit and scope of the devices and methods definedby the claims. Other aspects, advantages, and modifications areconsidered to be within the scope of the claims. The claims presentedare representative of the devices and methods disclosed herein. Other,presently unclaimed devices and methods, are also contemplated. Theinventors reserve the right to pursue such devices and methods in laterclaims.

The following examples serve to illustrate embodiments of the discloseddevices and methods and are given for illustrative purposes only and arenot intended to limit the present disclosure.

EXAMPLES

FIGS. 15, 16 and 17 show examples of pulse train supplied to the motoraccording to some embodiments. These figures show the discharge phase(510), in which power is supplied to the motor, the null phase (520) inwhich no power is supplied to the motor and the charge phase (530) whenpower is generated by the motor.

The pulse trains were tailored to reduce the power provided to the motorwhile each pulse rotates the motor by 20 degrees. The power source inthese examples is a zinc-air button battery, a 0.2 F capacitor and twophase motor commercially provided by Nidec Copal Corporation (U.S.A.).

The pulses are provided by PWM and/or by changing the pulse period.

Example 1

FIG. 15 shows a pulse train for rotating the motor by 160 degreescomposed of three sets of pulses:

-   -   The first set of pulses is applied for accelerating the motor        and includes three pulses lasting for 2.3 milliseconds.    -   The second set of pulses is designed for maintaining the motor        speed and includes four pulses, each having a 1.15 millisecond        period. This set of pulses rotates the motor by the same angle        as the first set but requires 50% less power. To increase the        energy efficiency, the last two pulses may have 80% width of the        duty cycle.    -   The third set of pulses is for stopping the motor and is        identical to the first set but in reversed phase.

In this example all the pulses have 100% pulse width (i.e., the pulsewidth equals the pulse duration).

Example 2

FIG. 16 shows a pulse train designed to rotate the motor by 520 degreesat a lower rotation velocity than that disclosed in Example 1. Thispulse train is composed of three sets of pulses:

-   -   The first set of pulses is applied for accelerating the motor        and includes four pulses lasting for 1.0 millisecond.    -   The second set of pulses is designed for maintaining the motor        speed and includes 22 pulses, each having a 0.7 millisecond        period. If the pulses in this set were tailored as the first set        (as described in the prior art), the energy consumption of this        set would be 40% higher.    -   The third set of pulses includes two stop pulses lasting for 1.0        millisecond, wherein a 90% duty cycle is applied to stop the        motor rotation.

Example 3

FIG. 17 shows a pulse train that does not apply power to stop the motor.The pulse train includes two sets of pulses:

-   -   The first set of pulses is applied for accelerating the motor        and includes four pulses lasting for 1.0 millisecond.    -   The second set of pulses is designed for maintaining the motor        speed and includes 22 pulses, each having a 0.7 millisecond        period.    -   Also shown are two pulses (530) supplied by the motor for        recharging the capacitor, i.e., the motor functions as a dynamo        by transferring kinetic energy to electrical power.

Example 3 requires less energy than the pulse train described in Example2 and provides two more steps to the motor (which are applied to stopthe motor in Example 2). The inertia of the motor at the end of thispulse train can be converted by the motor to electrical power, which canbe provided to other electrical components of the dispensing unit. Thispulse train requires 29.1 J, provides 26 steps of rotation and can alsoretrieve part of the excess power provided to the motor. A standardmethod of motor activation would be composed of 20 pulses lasting 1.0millisecond each, whereby at least two of them are applied for stoppingthe motor. Thus, less than 20 steps can be provided in this method.

1.-37. (canceled)
 38. A method for powering a medical device deliveringfluid to a body of a patient, the method comprising: providing a medicaldevice, the device including: a pump for dispensing a fluid; a steppermotor for activating the pump; and a power source for charging an energystorage component; accumulating energy in the energy storage componentduring a first period of time; and discharging the energy from theenergy storage component and providing the energy to the stepper motorin a form of pulsed power, during a second period of time.
 39. Themethod according to claim 38, wherein the energy discharged is furtherprovided to a plurality of energy consuming components including atleast one of: controller, communication device, sensing and monitoringdevice and a notification device.
 40. The method according to claim 39,wherein a ratio between the first period of time and the second periodof time is proportional to a ratio between a minimum power required toactivate the stepper motor and the components and a power provided bythe power source.
 41. The method according to claim 38, wherein a ratiobetween the first period of time and the second period of time isproportional to a ratio between a first minimum power required toactivate stepper motor and a second power provided by the power source.42. The method according to claim 38, wherein pulsed power provided tothe stepper motor comprises at least one pulse train pattern, the atleast one pulse train pattern comprising at least two different pulsesdiffering in at least one of: width, frequency, duty cycle, period,duration and energy delivered.
 43. The method according to claim 42,wherein each pulse of the at least two different pulses is configured torotate the stepper motor at a substantially identical angle, therotation activating the pump to dispense a substantially identicalamount of fluid.
 44. The method according to claim 42, whereindischarging the energy storage component comprising accelerating thestepper motor using at least one pulse of the at least one pulse trainpattern.
 45. The method according to claim 44, wherein discharging theenergy storage component further comprising rotating the stepper motorat a substantially constant velocity using at least one pulse of the atleast one pulse train pattern.
 46. The method according to claim 45,wherein discharging the energy storage component further comprisingdecelerating the stepper motor until substantially stopped using atleast one pulse of the at least one pulse train pattern.
 47. The methodaccording to claim 42, wherein discharging the energy storage componentcomprises: accelerating the stepper motor using at least one pulse ofthe at least one pulse train pattern, the at least one pulse having afirst amount of the discharged energy; rotating the stepper motor at asubstantially constant velocity using at least one pulse of the at leastone pulse train pattern, the at least one pulse having a second amountof the discharged energy, the second amount being substantially lowerthan the first amount; and decelerating the stepper motor until stoppedusing at least one pulse of the at least one pulse train pattern, the atleast one pulse having a third amount of the energy discharged, thethird amount is substantially different than the second amount;
 48. Themethod according to claim 45, further comprising providing substantiallyzero energy to the stepper for decelerating the stepper motor untilstopped.
 49. The method according to claim 48, further comprising:generating energy from deceleration of the stepper motor; and applyingthe generated energy to charge the energy storage component or tooperate energy consuming components.
 50. The method according to claim42, wherein at least one pulse of the at least two different pulsescomprises a first pulse portion during which the discharged energy isprovided to the stepper motor and a second pulse portion during whichthe discharged energy is not provided to the stepper motor.
 51. Themethod according to claim 42, wherein the at least one pulse trainpattern is configured to perform one or more of the following:maintaining a constant rotational velocity of the stepper motor;altering a rotational acceleration of the stepper motor; and altering arotational velocity of the stepper motor.
 52. The method according toclaim 38, further comprising: measuring rotational velocity of thestepper motor by a sensing and monitoring device; communicating themeasured rotational velocity to a controller; adjusting the dischargedenergy by the controller, based on the measured rotational velocity; andproviding the discharged energy to the stepper motor in the form of thepulsed power.
 53. The method according to claim 38, wherein the firstperiod of time and the second period of time at least partially overlap.54. The method according to claim 42, wherein the at least one pulsetrain pattern is at least one of adjusted and scheduled based on energystored in the energy storage component.
 55. A medical device fordelivering a fluid to a body of a patient, the medical devicecomprising: a pump for dispensing a fluid; a stepper motor foractivating the pump; and a power source for charging an energy storagecomponent; wherein, the energy storage component is configured foraccumulating energy during a first period of time and discharging theenergy during a second period of time, the discharged energy beingprovided to the stepper motor in a form of pulsed power.
 56. The deviceaccording to claim 55, wherein a ratio between the first period of timeand the second period of time is proportional to a ratio between aminimum power required to activate the stepper motor and a powerprovided by the power source.
 57. The device according to claim 55,wherein pulsed power is provided to the stepper motor using at least onepulse train pattern, the at least one pulse train pattern comprising atleast two different pulses differing in at least one of: width,frequency, duty cycle, period and energy delivered.
 58. The deviceaccording to claim 57, wherein each pulse of the at least two differentpulses is configured to rotate the stepper motor a substantiallyidentical angle, wherein the rotation of the stepper motor activates thepump to dispense an identical amount of fluid.
 59. The device accordingto claim 57, wherein the stepper motor is accelerated using at least onepulse of the at least one pulse train pattern.
 60. The device accordingto claim 59, wherein the stepper motor is rotated at a substantiallyconstant velocity using at least one pulse of the at least one pulsetrain pattern.
 61. The device according to claim 60, wherein the steppermotor is decelerated until stopped using at least one pulse of at leastone pulse train pattern.
 62. The device according to claim 57, wherein:the stepper motor is accelerated using at least one pulse of the atleast one pulse train pattern, the at least one pulse having a firstamount of the discharged energy; the stepper motor is rotated at aconstant velocity using at least one pulse of the at least one pulsetrain pattern, the at least one pulse having a second amount of thedischarged energy, the second amount is substantially lower than thefirst amount; and the stepper motor is decelerated until stopped usingat least one pulse of at least one pulse train pattern, the at least onepulse having a third amount of the discharged energy, the third amountis substantially different than the second amount;
 63. The deviceaccording to claim 59, wherein substantially zero energy is provided tothe stepper motor to decelerate the stepper motor until stopped.
 64. Thedevice according to claim 63, wherein energy is generated fromdeceleration of the stepper motor, wherein the energy generated is usedfor at least one of charging the energy storage component and operatingother components of the device.
 65. The device according to claim 57,wherein at least one pulse of the at least two different pulsescomprises a first pulse portion during which the discharged energy isprovided to the stepper motor and a second pulse portion during whichthe discharged energy is not delivered to the stepper motor.
 66. Thedevice according to claim 55, wherein the device further comprises acontroller.
 67. The device according to claim 66, wherein the controlleris configured to at least one of adjusting and scheduling the at leastone pulse train pattern based on the energy stored in the energy storagecomponent.
 68. The device according to claim 66, further comprising asensing and monitoring device for measuring rotational velocity of thestepper motor and communicating the measured rotational velocity to thecontroller, the controller is configured to adjust the discharged energybased on the measured rotational velocity.
 69. The device according toclaim 55, wherein the energy storage component comprises a capacitor.70. The device according to claim 55, wherein the power source is azinc-air battery.
 71. The device according to claim 69, wherein theenergy storage component comprises a high capacity capacitor having acapacity from about 180 mF to about 200 mF.
 72. The device according toclaim 55, wherein the device further comprises a DC-DC converter toprovide voltage required by energy consuming components.
 73. The deviceaccording to claim 55, further comprising: a reusable part containingthe stepper motor and electronic components, the electronic componentsinclude at least the energy storage component; and a disposable parthaving a reservoir and a power source; wherein, upon connection of thereusable part and the disposable part: the power source charges theenergy storage component; the discharged energy is provided to thestepper motor and to the electronic components; and fluid is dispensedfrom the reservoir to the body of the patient.
 74. The medical deviceaccording to claim 55, further comprising: a skin adherable cradle unit;and a dispensing unit having the pump and stepper motor, the dispensingunit being at least one of connectable to and disconnectable from thecradle unit.
 75. The device according to claim 55, further comprising aplurality of energy consuming components including at least one of:controller, communication device, sensing and monitoring device and anotification device, wherein the discharged energy is further providedto the energy consuming components.
 76. The device according to claim75, wherein a ratio between the first period of time and the secondperiod of time is proportional to a ratio between a minimum powerrequired to activate the stepper motor and the energy consumingcomponents and a power provided by the power source.